Avaliação da resistência de união de adesivos universais à dentina

Abstract

The aim of this study was to evaluate, in vitro, the tensile bond strength to dentin of the adhesive systems Single Bond Universal (3M), All-Bond Universal (Bisco) and One Coat 7 (Coltène), in the self-etch mode, taking Clearfil SE Bond as control. The middle portion of 120 bovine teeth were included in a selfcured acrylic resin and abraded in a mechanic lathe with water refrigeration in order to obtain a plane surface in dentin. The adhesives systems were applied on the dentin in accordance with the instructions of the manufacturers, followed by the application of composite resin Z250 (3M). Thirty specimens were obtained for each adhesive system. After immersion in distilled water at 37 oC for 24 hours, half of the specimens were submitted to cyclic loading using 500,000 cycles. For all specimens, the tensile bond strength was determinated in a universal testing machine (EMIC DL-2000) at a cross-head speed of 0.5 mm/minute. The results were analyzed by two-way ANOVA and Tukey’s test (α = 5%). The interaction between the factors adhesive system and cyclic loading was significant (p<0.05). The means followed by the same letter represent no statistical difference for the tensile bond strength (MPa) after 24 h: One Coat 7 = 7.86A (±2.90), Single Bond Universal = 6.78AB (±2.03), All-Bond Universal = 5.61BC (±2.32), Clearfil SE Bond = 3.53C (±1.89). After cyclic loading, the adhesive systems Clearfil SE Bond, Single Bond Universal and All-Bond Universal maintained the bond strength values comparable to 24 h period. There was a significant decrease only for One Coat 7. The adhesive system Single Bond Universal, All-Bond Universal and One Coat 7, in the self-etch mode, had bond strength to dentin comparable to Clearfil SE Bond. Only the adhesive system One Coat 7 decreased the bond strength to dentin after cyclic loading.